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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_BASE_CHANNEL_MIXING_MATRIX_H_
#define MEDIA_BASE_CHANNEL_MIXING_MATRIX_H_
#include <vector>
#include "base/macros.h"
#include "media/base/channel_layout.h"
#include "media/base/media_export.h"
namespace media {
class MEDIA_EXPORT ChannelMixingMatrix {
public:
ChannelMixingMatrix(ChannelLayout input_layout,
int input_channels,
ChannelLayout output_layout,
int output_channels);
~ChannelMixingMatrix();
// Create the transformation matrix of input channels to output channels.
// Updates the empty matrix with the transformation, and returns true
// if the transformation is just a remapping of channels (no mixing).
bool CreateTransformationMatrix(std::vector<std::vector<float>>* matrix);
private:
// Result transformation of input channels to output channels
std::vector<std::vector<float>>* matrix_;
// Input and output channel layout provided during construction.
ChannelLayout input_layout_;
int input_channels_;
ChannelLayout output_layout_;
int output_channels_;
// Helper variable for tracking which inputs are currently unaccounted,
// should be empty after construction completes.
std::vector<Channels> unaccounted_inputs_;
// Helper methods for managing unaccounted input channels.
void AccountFor(Channels ch);
bool IsUnaccounted(Channels ch) const;
// Helper methods for checking if |ch| exists in either |input_layout_| or
// |output_layout_| respectively.
bool HasInputChannel(Channels ch) const;
bool HasOutputChannel(Channels ch) const;
// Helper methods for updating |matrix_| with the proper value for
// mixing |input_ch| into |output_ch|. MixWithoutAccounting() does not
// remove the channel from |unaccounted_inputs_|.
void Mix(Channels input_ch, Channels output_ch, float scale);
void MixWithoutAccounting(Channels input_ch, Channels output_ch, float scale);
DISALLOW_COPY_AND_ASSIGN(ChannelMixingMatrix);
};
} // namespace media
#endif // MEDIA_BASE_CHANNEL_MIXING_MATRIX_H_
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